Drug interactions
Chlorothiazide + Formoterol
Severity: Moderate
Chlorothiazide and Formoterol: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Thiazide diuretics cause renal potassium loss, and formoterol drives potassium into cells. Together they can cause significant hypokalemia, which may provoke arrhythmias, particularly in those with cardiac disease or hypoxia.
What this interaction means in plain words
Chlorothiazide and Formoterol can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Chlorothiazide belongs to Cardiovascular; Formoterol belongs to Respiratory.
Why it happens
Additive hypokalemia from thiazide-induced renal potassium wasting and beta-2 mediated cellular potassium uptake.
What to do
Monitor serum potassium, especially when starting therapy or at higher formoterol doses, and supplement potassium as needed.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Formoterol
- Adagrasib + Formoterol Major
- Amiodarone + Formoterol Major
- Amisulpride + Formoterol Major
- Amitriptyline + Formoterol Major
- Amoxapine + Formoterol Major
- Arformoterol + Formoterol Major
Other interactions of Chlorothiazide
Frequently asked questions
Can I take Chlorothiazide with Formoterol?
MediHelp rates the interaction as moderate. Chlorothiazide and Formoterol can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Thiazide diuretics cause renal potassium loss, and formoterol drives potassium into cells. Together they can cause significant hypokalemia, which may provoke arrhythmias, particularly in those with cardiac disease or hypoxia.
How serious is the interaction between Chlorothiazide and Formoterol?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor serum potassium, especially when starting therapy or at higher formoterol doses, and supplement potassium as needed.
What other medicines interact with Formoterol?
MediHelp also lists interactions of Formoterol with, for example, Adagrasib, Amiodarone, Amisulpride. The full list is on the Formoterol page.
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